Image forming devices including copiers, laser printers, facsimile machines, and the like, include a photoconductive drum (hereinafter referred to as a drum) having a rigid cylindrical surface that is coated along a defined length of its outer surface. The surface of the drum is charged to a uniform electrical potential and then selectively exposed to light in a pattern corresponding to an original image. Those areas of the photoconductive surface exposed to light are discharged thus forming a latent electrostatic image on the photoconductive surface. A developer material, such as toner, having an electrical charge such that the toner is attracted to the photoconductive surface is brought into contact with the drum""s photoconductive surface. A recording sheet, such as a blank sheet of paper or a transfer belt, is then brought into contact with the photoconductive surface and the toner thereon is transferred to the recording sheet in the form of the latent electrostatic image. The recording sheet is then heated thereby permanently fusing the toner to it.
In preparation for the next image forming cycle, the photoconductive surface is optionally discharged and cleaned of residual toner. A cleaner blade is positioned adjacent to the drum for removing the residual toner that has not been transferred during the printing process. Removal of the residual toner is necessary prior to preparing the drum to receive a new image.
Conventional cleaner blades are manufactured by stamping and forming a bracket from a sheet metal stock, then molding or adhering a flexible elastomer member to the bracket. This assembly is attached to the printer in proximity to the drum such that the flexible member is deflected and pressed against the surface of the drum. There are often manufacturing difficulties in these conventional designs resulting from variations in the properties of the sheet such as the thickness and temper. These variations cause deviations from the desired form resulting in inconsistent removal of the residual toner across the length of the drum.
It is further desirable for the image forming apparatus to have the smallest dimensions possible. This is a key selling point to consumers who desire the small dimensions because the apparatus is easier to manipulate and move, and occupies a minimal amount of desk space in a workstation where available space is often at a premium. As a result of the smaller sizes, these internal elements of the image forming apparatus are located in a very compact space. Element designs used in physically larger printers may not be applicable to the smaller-sized apparatus because of the large dimensions. Thus, it is necessary to reduce the physical size of the elements.
The invention is directed to a device for mounting a charge roller against a photoconductive drum within an image forming apparatus. The device includes a bracket having a first guide and a second guide for mounting the charge roller. In one embodiment, the charge roller is movably positioned within the guides. In one embodiment, one or more biasing devices bias the charge roller against the photoconductive drum. Bearings may be positioned within the guides for mounting the charge roller axle. The bearings are movable within the guides.
In one embodiment, the bracket is constructed of an electrically conductive material. The bracket may be positioned within the image forming apparatus to contact an electrical connection. The electrical charge is then delivered to the bracket and to the charge roller. The bracket may include a connection that is sized and oriented to contact the electrical connection of the image forming apparatus.
In one embodiment, a cleaner blade is attached to the bracket. The cleaner blade extends along at least a portion of the photoconductive drum to remove residual toner.